Oil separators are used in refrigeration systems to remove the compressor lubricating oil aerosol from the hot, high pressure compressor discharge refrigerant vapor, e.g., R-12, R-22, R-502, and to return this oil to the compressor oil sump, which is essentially at suction pressure. This function benefits the compressor during periods of marginal lubrication. This function also improves the cooling effectiveness of the entire refrigeration system, as this oil/refrigerant aerosol would normally penalize the refrigeration system by diminished heat transfer through the condenser and evaporator coils, and by reduced compressor volumetric efficiency from diminished refrigerant mass flow rate. The oil separator prevents these functional problems by intercepting this compressor oil before it can circulate through the refrigeration system, and returning it directly back to the oil sump.
There are two general classes of refrigeration oil separators, classified by their different methods of pressure reduction, whereby oil removed from the high pressure side of the compressor is returned to the low pressure oil sump. One type uses a ball-float valve to meter oil flow from an oil separator reservoir. This type of oil separator is vulnerable to mechanical vibration and shock, and is thus more appropriate for static or fixed refrigeration systems. The other class of oil separators uses a restrictive orifice, such as a capillary tube, to return the oil to the low pressure sump. This type is not affected by vibration and shock, and may be used in transport refrigeration systems, for example.
Oil separators for smaller capacity refrigeration systems, such as transport refrigeration systems used for cooling the cargoes of trucks, trailers, and containers, are relatively costly, they have marginal performance effectiveness, and they require vertical axis installation. The orientation limitation is due to the fact that the capillary oil-return tube depends upon gravity to return the separated oil. The vertical axis orientation limitation can present awkward installation difficulties, particularly in many truck refrigeration applications with very confined access space.
Thus, it would be desirable and it is an object of the invention to provide a new and improved oil separator suitable for high vibration and shock environments, which is relatively inexpensive, is highly effective without excessive pressure drop, and which does not require vertical axis mounting.